Smoking is a leading cause of preventable disease in industrialized countries, especially cardiovascular and respiratory illness, and cancer. In 2000, the US Department of Health and Human Services issued an evidenced-based Clinical Practice Guideline on Treating Tobacco Use and Dependence that states that patients who smoke, but are unwilling to quit, should receive an intervention that increases their motivation to quit. Among the motivations listed is highlighting the risks of cigarette smoking. One of these risks is decreased lung function as measured by spirometry. However, the evidence that spirometry enhances smoking cessation is limited. The Agency for Healthcare Research and Quality (AHRQ) recently concluded that the available evidence does not support the use of spirometry in the primary care setting in order to improve smoking cessation rates. Nonetheless, in recognition of the potential importance of this tool, the AHRQ lists the need for randomized controlled trials to determine the role of spirometry in smoking cessation as a priority of future research. Before such controlled trials can take place, we need to understand why spirometry has not been shown to convincingly enhance smoking cessation. We believe that the primary reason spirometry has failed in this regard is because the meaning of the measurement in the context of the importance of smoking cessation is not effectively communicated to the patient who smokes. To test this hypothesis, we have designed this proposal to develop an enhanced [spirometry intervention, to include a motivational message and follow-up letter], and then test the impact of this [intevention] on the quit attempt rate. We hypothesize that providing knowledge of lung function to current smokers through an enhanced [spirometry intervention] will increase the quit attempt rate compared to delivery of these results through a standard [intervention]. Our 3 Specific Aims are: 1) To develop an enhanced motivational message about spirometry using principles of behavioral and communication theory;2) To determine the effect of delivering spirometry results to current smokers through an enhanced [spirometry intervention] on the quit attempt rate;3) To determine which clinical characteristics are associated with quit attempts, and identify barriers to the effectiveness of spirometry in enhancing the quit attempt rate. These data will provide the framework for developing a future large clinical trial of the effectiveness of spirometry on smoking cessation. Cigarette smoking is the leading cause cancer-related death in the world. Therefore, quitting smoking is the most important behavioral intervention in cancer control. This project will determine whether measuring lung function in smokers and delivering the results to them using a strong motivational strategy will increase the likelihood that they will try to stop smoking. If so, then this strategy can be used in a large scale study to determine whether lung function results are effective in getting people to quit smoking.